System and method for transformer repair

ABSTRACT

A system includes a portable transformer repair station that includes a portable building. The portable building includes a framework, a roof, and walls having a disassembled building configuration and an assembled building configuration. The portable building is configured to be transported in the disassembled building configuration. The portable building is configured to enclose a transformer repair space in the assembled building configuration. The portable transformer repair station also includes a portable floor having a disassembled floor configuration and an assembled floor configuration. The portable floor is configured to be transported in the disassembled floor configuration. The portable floor is configured to be disposed within the portable building in the assembled floor configuration. The portable transformer repair station also includes a portable oven configured to be disposed within the portable building. The portable oven is configured to remove moisture from a core and coils of a high voltage power transformer.

BACKGROUND OF THE INVENTION

The disclosed subject matter relates to large power distribution transformers, such as transformers disposed at a power plant that generates and distributes electricity to a power grid. More specifically, the disclosed subject matter relates to repair of these large power distribution transformers.

Transformers are devices that transfer electrical energy from one circuit to another through inductively coupled conductors, namely coils of the transformer. Transformers may be used to step up, or increase, or step down, or decrease, the voltage of an alternating current. In certain transformers, the coil consists of windings of wire wound around a ferromagnetic core. During use, transformers may be subject to maintenance issues, such as coronas, electrical breakdowns, internal arcing, and so forth. Thus, transformers may undergo regular maintenance to help prevent such maintenance issues. For example, some transformers may be rewound on a regular basis, which involves removing the windings from the cores of the transformer and installing new windings around the cores. Such transformer rewinds may be performed at a transformer repair shop remote from the facility where the transformer is installed. Thus, the entire transformer may be transported to the repair shop for the rewinding. Unfortunately, the transportation of large, high voltage power transformers may be expensive. For example, the transformers may weigh thousands of kilograms, and may be tens and hundreds of cubic meters in size. Thus, the transportation may require use of large semi-trailer trucks and/or railway carriers. In addition, the repair shop may be far from the transformer facility, thereby increasing the duration of the maintenance outage associated with the transformer rewind.

BRIEF DESCRIPTION OF THE INVENTION

Certain embodiments commensurate in scope with the originally claimed invention are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the invention may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

In a first embodiment, a system includes a portable transformer repair station. The portable transformer repair station includes a portable building. The portable building includes a framework, a roof, and walls having a disassembled building configuration and an assembled building configuration. The portable building is configured to be transported in the disassembled building configuration. The portable building is configured to enclose a transformer repair space in the assembled building configuration. The roof and the walls include at least one fabric sheet. The portable transformer repair station also includes a portable floor having a disassembled floor configuration and an assembled floor configuration. The portable floor is configured to be transported in the disassembled floor configuration. The portable floor is configured to be disposed within the portable building in the assembled floor configuration. The portable transformer repair station also includes a portable oven configured to be disposed within the portable building. The portable oven is configured to remove moisture from a core and coils of a high voltage power transformer.

In a second embodiment, a system includes a portable transformer repair station. The portable transformer repair station includes a portable transformer enclosure that includes walls surrounding an interior chamber configured to house a core and coils of a high voltage power transformer. The portable transformer repair station also includes a moisture removal unit configured to remove moisture from the interior chamber and a temperature controller configured to adjust the moisture removal unit to reduce a moisture level below a threshold moisture level in the interior chamber to substantially dry the core and coils of the high voltage power transformer.

In a third embodiment, a method includes transporting a portable transformer repair station to a local site surrounding a transformer site. The portable transformer repair station includes a portable building, a portable floor, and a portable oven. The method also includes assembling the portable floor at the local site, assembling the portable building at the local site, placing the portable oven inside the portable building, and drying a core and coils of a high voltage power transformer in the portable oven.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

FIG. 1 is a perspective view of an embodiment of a high voltage power transformer;

FIG. 2 is a schematic diagram of an embodiment of a portable transformer repair station;

FIG. 3 is a perspective view of a portable building of an embodiment of a portable transformer repair station;

FIG. 4 is a perspective view of a portable floor of an embodiment of a portable transformer repair station;

FIG. 5 is a perspective view of a portable oven of an embodiment of a portable transformer repair station;

FIG. 6 is a perspective view of a transformer rack of an embodiment of a portable transformer repair station;

FIG. 7 is a side view of a group of trailers used to transport an embodiment of a portable transformer repair station; and

FIG. 8 is a flowchart of a process for using a portable transformer repair station.

DETAILED DESCRIPTION OF THE INVENTION

One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

As discussed in detail below, the disclosed embodiments provide systems and methods for repairing high voltage power transformers using a portable transformer repair station. High voltage power transformers may be used in the power distribution industry for stepping up or stepping down high voltage alternating currents (e.g., greater than approximately 35,000 volts). Again, the transformers may be used at power plants that generate and distribute electricity, e.g., tens, hundreds, or thousands of megawatts of electricity. Thus, the transformers are large and heavy, e.g., thousands of kilograms, and tens and hundreds of cubic meters in size. Occasionally, the coils of such transformers may be rewound to help prevent unscheduled maintenance outages caused by coronas, electrical breakdowns, internal arcing, and so forth. Prior to a scheduled maintenance outage, the portable transformer repair station is transported to a transformer facility and assembled. The transformer is then taken out of service, prepared, and disassembled in the portable transformer repair station to remove the coils from the core of the transformer. The coils may be shipped from the facility to a transformer repair shop to be rewound, thereby reducing transportation costs compared to shipping the entire transformer to the repair shop. The rewound coils may be shipped from the repair shop to the facility and installed on the core in the portable transformer repair station. Alternatively, new coils may be shipped from the repair shop and installed on the core in the portable transformer repair station, thereby reducing the duration of the scheduled maintenance outage. The core and coils are dried in the portable transformer repair station and installed in the transformer, which is returned to service. The portable transformer repair station may be disassembled and transported to another facility.

The portable transformer repair station may include a portable building, a portable floor, and a portable oven. The portable building may include a framework, a roof, and walls having a disassembled building configuration and an assembled building configuration. In other words, the portable building is not a permanent structure and may be transported from one facility (e.g., power plant) to another. Thus, the portable building may be used to repair transformers in the assembled building configuration and transported in the disassembled building configuration. In the assembled building configuration, the portable building may enclose a transformer repair space where the transformer may be prepared, disassembled, dried, reassembled, and so forth. In addition, the roof and the walls of the portable building may include at least one fabric sheet. The portable floor may have a disassembled floor configuration and an assembled floor configuration. In other words, the portable floor is also not a permanent structure. Thus, the portable floor may be used in the portable building in the assembled floor configuration and transported in the disassembled floor configuration. The portable oven may be disposed in the portable building and used to remove moisture from the core and coils of the high voltage power transformer. In further embodiments, the portable transformer repair station may include a temperature controller that adjusts the portable oven to reduce a moisture level below a threshold moisture level to substantially dry the core and coils of the high voltage power transformer.

Turning to the drawings, FIG. 1 is a perspective view of a high voltage power transformer 10. Specifically, the high voltage power transformer 10 depicted in FIG. 1 may be a three phase distribution transformer. Thus, the core of the transformer 10 may include a first winding leg 12, a second winding leg 14, and a third winding leg 16. The transformer 10 also includes an upper yoke 18 and a lower yoke 20. In certain embodiments, the winding legs 12, 14, and 16, and the upper and lower yokes 18 and 20 may include a plurality of laminations formed from a magnetic material, such as, but not limited to, silicone steel, amorphous alloy, and so forth. A cylindrical phase winding 22 is positioned on each of the winding legs 12, 14, and 16. Each phase winding 22 includes a low voltage primary winding 24 and a concentric, high voltage secondary winding 26 located radially outward of the primary winding 24. The primary and secondary windings 24 and 26 are each formed by multiple layers, or coils, of conductive cabling connected in series. Each layer is formed by a plurality of turns of the conductive cabling connected in series.

The conductive cabling used to form the phase windings 22 may be non-insulated cabling. The use of non-insulated cabling necessitates the placement of an electrically-insulative material within the phase windings 22. More particularly, a solid, electrically-insulative material such as epoxy resin may be placed between adjacent turns, and between adjacent layers within the phase winding 22. The phase windings of oil-filled transformers are further insulated by oil (e.g., mineral oil) that surrounds the phase windings within such transformers. The placement of insulation between the adjacent turns and layers of the phase winding 22 is configured to prevent short-circuiting that would otherwise occur due to the differing electric potential between the adjacent layers and turns. The insulation is also configured to prevent short circuiting between adjacent phase windings 22, and between the phase windings 22 and adjacent conductive components. The solid insulative material is placed individually over each cable layer, and between adjacent turns in the particular layer, immediately after the layer has been wound. Hence, installation of the solid insulative material is integrated into the winding process for each phase winding 22.

During a rewind of the high voltage power transformer 10, the upper and lower yokes 18 and 20 may be separated from the winding legs 12, 14, and 16. Subsequently, the phase windings 22 may be removed from the winding legs 12, 14, and 16. Next, new or rewound phase windings 22 may be installed in the winding legs 12, 14, and 16. The upper and lower yokes 18 and 20 may be reassembled with the winding legs 12, 14, and 16 and the windings 22, yokes 18 and 20, and legs 12, 14, and 16 may be dried before placing the high voltage power transformer 10 back into service. Drying of the phase windings 22 prior to placing the transformer 10 in service may help prevent internal arcing or coronas, for example. Several methods may be used to dry the phase windings 22 of the transformer 10. For example, in hot air vacuum drying, hot air is circulated over the phase windings 22 followed by periods of vacuum. Use of periods of vacuum helps to remove additional moisture from the phase windings 22. In vapor phase drying, an evaporated solvent condenses on colder parts of the transformer 10. The solvent is then removed along with any moisture. In some transformers 10, low frequency heating may be used, in which a current at a lower frequency than the nominal current of the transformer 10 is used to heat the phase windings 22 and drive off any moisture. Any of these methods, or other methods of drying transformer components, may be used in the portable transformer repair station described in detail below.

FIG. 2 is a schematic diagram of a portable transformer repair station 40 that may be used to dry the core and coils of transformer 10 on-site at a power plant or other facility having one or more transformers 10 (e.g., 1 to 100 transformers). Although one arrangement of components of the portable transformer repair station 40 is shown in FIG. 2, other arrangements and configurations are possible as well. Specifically, the portable transformer repair station 40 may include a portable building 42 that encloses the various components of the portable transformer repair station 40 as discussed in detail below. For example, the building 42 may include a framework supporting a fabric exterior, e.g., walls, ceiling, and/or roof. The framework may be erected first and then covered with the fabric exterior for the assembled configuration of the building 42. A certain portion of the interior of the portable building 42 may be used as a transformer repair space 44, in which the preparation, disassembly, drying, and assembly of the transformer 10 is performed. In addition, the portable building 42 covers a portable floor 46, which is described in detail below. For example, the floor 46 may include one or more sections that fit together, stack on top of one another, and/or interlock with one another, wherein the sections may include cushioning, flame resistant, and/or water resistant materials. Furthermore, the floor 46 eliminates the need for a permanent foundation, such as a concrete slab. A portable oven 48 may be disposed within the transformer repair space 44 and used to dry the core and coils of the transformer 10. For example, the phase windings 22, winding legs 12, 14, and 16, and upper and lower yokes 18 and 20 of the transformer 10 may be placed in the portable oven 48 to be dried after a rewind. In certain embodiments, one or more heaters 50 may be used to direct hot air into the portable oven 48 for drying of the core and coils of the transformer 10. The heaters 50 may be electric heaters, combustion-based heaters, or any other type of heater. For example, the heaters 50 use electrical resistance, combustion of a liquid or gas fuel, or any combination thereof, to generate the hot air (e.g., air greater than approximately 100 degrees Celsius). In addition, the heaters 50 may be portable heaters that are shipped together with the rest of the portable transformer repair station 40. In certain embodiments, the portable building 42 may include one or more core storage racks 52, which may be used to store the winding legs 12, 14, and 16 and/or upper and lower yokes 18 and 20 of the transformer 10 when not being dried in the portable oven 48. In further embodiments, one or more heating ventilation and air conditioning (HVAC) units 54 may be disposed outside of the portable building 42 to provide heating or air conditioning to regulate a temperature and/or humidity within the portable building 42. As discussed in detail below, the various components of the portable transformer repair station 40 may be transported to a transformer facility in a disassembled configuration on one or more trailers and assembled into an assembled configuration for drying of the core and coils of the transformer 10. After drying of the core and coils of transformer 10 is complete, the portable transformer repair station 40 may be disassembled into the disassembled configuration and placed on the trailers to be transported to another facility. Thus, the portable transformer repair station 40 is not a permanent structure.

FIG. 3 is a perspective view of the portable building 42 in the assembled configuration. As shown in FIG. 3, the portable building 42 may include a front side 70 and a back side 72. A roof and walls 74 of the portable building 42 may be supported on a front support 76, a back support 78, and one or more intermediate supports 80, which collectively may be referred to as a framework of the portable building 42. The roof and walls 74 may be made from at least one fabric sheet. In certain embodiments, the roof and walls 74 may be made from a flame retardant material (e.g., a cotton fabric impregnated with a flame retardant chemical; a vinyl and polynosic rayon blend; an aramid synthetic fiber; a meta-aramid and para-aramid fiber blend; a meta-aramid, para-aramid, and modacrylic fiber blend; an oxidized polyacrylonitrile and aramid fiber blend; or a combination thereof), a moisture resistant material (e.g., fluoropolymers, sulfonated polymers, polyamides, polyimides, cellulosic polymers, expanded polytetrafluoroethylene (ePTFE), or a combination thereof), and/or an ultraviolet light resistant material (e.g., poly(methyl methacrylate, polycarbonate, PTFE, polyethylene terephthalate, or a combination thereof), such as polyvinylchloride (PVC). In other embodiments, the roof and walls 74 may be made from an electrically non-conductive, insulating, and/or static free material. In certain embodiments, the roof and walls 74 may include two or more sheets, or layers, of fabric. In further embodiments, the supports 76, 78, and 80 may be made from a metal, such as galvanized steel or aluminum. In some embodiments, the portable building 42 may include a roof hatch 82, which may be used for ventilation and/or access. In addition, the portable building 42 may include a personnel door 84 and an equipment door 86 on the front side 70. The personnel door 84 may be used to enable personnel to enter and exit the portable building 42. The larger equipment door 86 may be used to move the transformer 10 in and out of the portable building 42. For example, the transformer 10 may be moved using a forklift or similar device. In addition, the portable building 42 may be defined by a width 88 and a length 90. For example, the width 88 and/or the length 90 may be between approximately 12 meters (m) to 24 m, 15 m to 21 m, or 16 m to 19 m. In addition, the portable building 42 may be defined by a height 92. In certain embodiments, the height 92 may be between approximately 9 m to 15 m, 11 m to 14 m, or 12 m to 13 m. The equipment door 86 may also be defined by a width 94 and a height 96. In certain embodiments, the width 94 and/or the height 96 may be between approximately 3 m to 12 m, 4 m to 9 m, or 5 m to 8 m. In other embodiments, the portable building 42 may have different shapes, sizes, and/or configurations. In one embodiment, the portable building 42 may be obtained from Big Top Manufacturing of Perry, Fla.

FIG. 4 is a perspective view of the portable floor 46 that may be used with the portable building 42. As illustrated in FIG. 4, the portable floor 46 may include a plurality of floor segments, or portions, such as a first portion 110 and a second portion 112, which may be selectively assembled together and later disassembled. A plurality of the portions 110 and 112 may be used to cover the floor of the portable building 42. For example, the floor 46 may include between approximately 25 to 65, to 55, or 35 to 45 portions 110 and 112 to cover the ground (e.g., bare ground without concrete slab or other foundation) under the portable building 42. In certain embodiments, the portions 110 and 112 may include an upper cushioning material 114 and a lower supporting material 116. For example, the surface of the cushioning material 114 may include one or more traction nubs 117 to provide traction with personnel or vehicles moving in the portable building 42. The supporting material 116 may include an interior of structural supports that helps reduce the weight of the portable floor 46 while providing sufficient strength. As shown in FIG. 4, the first and second portions 110 and 112 may selectively couple to one another. For example, the first portion 110 may include one or more first locking portions 118 disposed about a periphery of the cushioning material 114 of the first portion 110. Similarly, the second portion 112 may include a plurality of second locking portions 120 disposed about a periphery of the supporting material 116 of the second portion 112. Each of the first and second locking portions 118 and 120 may be aligned along an axis 122. Once aligned along the axis 122, the first and second portions 110 and 112 may be brought together to be locked by, for example, turning the first locking portions 118 to engage the second locking portions 120.

In certain embodiments, the cushioning material 114 of the portable floor 46 may be defined by a thickness 124, and the structural material 116 may be defined by a thickness 126. In certain embodiments, the thicknesses 124 and/or 126 may be between approximately 10 centimeters (cm) to 12 cm, 8 cm to 14 cm, or 6 cm to 16 cm. Accordingly, the portable floor 46 may be defined by an overall height 128, which may be approximately the sum of the thicknesses 124 and 126. For example, the height 128 may be between approximately 12 cm and 36 cm, 16 cm to 28 cm, or 20 cm to 24 cm. As shown in FIG. 4, the first and second portions 110 and 112 overlap one another by an overlap distance 130. In certain embodiments, the overlap distance 130 may be between approximately 25 cm to 102 cm, 36 cm to 76 cm, or 46 cm to 66 cm. The cushioning portion 114 may be defined by a length 132 and a width 134. In certain embodiments, the length 132 may be between approximately 4 m to 5 m, 3 m to 6 m, or 2 m to 7 m and the width 134 may be between approximately 2 m to 3 m, 1.5 m to 4 m, or 1 m to 5 m. The structural material 116 may have similar dimensions. In various embodiments, the portable floor 46 may be made from a material that provides strength, rigidity, and impact resistance, such as, but not limited to, high density polyethylene. In certain embodiments, an anti-static (static dissipative) additive may be incorporated into the material used for the portable floor 46. In other embodiments, the portable floor 46 may be made from a flame retardant material and/or a moisture resistant material. The first and second portions 110 and 112 of the portable floor 46 may be taken apart and stacked for transport in the dissembled configuration. In one embodiment, the portable floor 46 may be obtained from Signature Fencing & Flooring Systems, LLC of New York, N.Y.

FIG. 5 is a perspective view of the portable oven 48, or moisture removal unit, that may be placed in the transformer repair space 44 of the portable building 42. As described above, the core and coils of the transformer 10 may be placed in the portable oven 48 to remove moisture from the phase windings 22 and insulation of the transformer 10. As with the portable building 42, the portable oven 48 may be easily transitioned between an assembled configuration and a disassembled configuration. As shown in FIG. 5, the portable oven 48 includes a front side 150 and a back side 152. In addition, the portable oven 48 includes walls 154 and a roof 156. The walls 154 and the roof 156 may be made from a metal, such as galvanized steel or aluminum, and may include a supporting framework. The walls 154 and the roof 156 may be made from a plurality of segments that may be attached together to erect the portable oven 48 into an assembled oven configuration and disassembled and stacked on top of one another to place the portable oven 48 into a disassembled oven configuration. In addition, one or more openings may be formed in the walls 154 to enable hot air from the heaters 50 to enter the portable oven 48. In other embodiments, the portable oven 48 may also include a heat exchanger, an induced draft fan, a coalescing filter, or any combination thereof, to facilitate drying of the core and coils of the transformer 10. A first personnel door 158 and a second personnel door 160 may be included in the walls 154 for personnel access. An equipment door 162 (e.g., a vertical sliding door) may be included in one or more of the walls 154 to enable the core and coils of the transformer 10 to be moved in and out of the portable oven 48. The portable oven 48 may be defined by a width 164 and a length 166. In certain embodiments, the width 164 may be between approximately 3 m to 8 m, 4 m to 7 m, or 5 m to 6 m. In other embodiments, the length 166 may be between approximately 8 m to 15 m, 9 m to 14 m, or 10 m to 12 m. In addition, the portable oven 48 may be defined by a height 168, which may be between approximately 4 m to 8 m, 5 m to 7 m, or 5.5 m to 6 m. The equipment door 162 may be defined by a width 170 and a height 172. In certain embodiments, the width 170 and/or height 172 may be between approximately 3 m to 11 m, 4 m to 9 m, or 5 m to 8m. In certain embodiments, the walls 154 and/or the roof 156 may be insulated to help retain heat within the portable oven 48. For example, the portable oven 48 may be insulated with materials such as, but not limited to, polyisocyanurate, fiberglass, mineral wool, polystyrene, polyurethane, vermiculite, cellulose, or a combination thereof. In certain embodiments, the portable oven 48 may be placed upon the portable floor 46 or may include a separate floor. The portable oven 48 may include one or more sensors 174 to provide feedback regarding a temperature or humidity in the portable oven 48. In one embodiment, the portable oven 48 may be obtained from Kelly Group, Inc. of Fremont, Nebr.

FIG. 6 is a perspective view of a core storage rack 52, or transformer rack, which may be used to store the cores of the transformer 10. Specifically, the core storage rack 52 includes a rack 190 and a pallet 192. The pallet 192 may be configured to hold the winding legs 12, 14, and 16 and/or the upper and lower yokes 18 and 20 of the transformer 10. The pallet 192 may be coupled to the rack 190 using one or more brackets 194. The bracket 194 may be attached to one or more vertical support legs 196 (e.g., two legs) of the rack 190. The vertical support legs 196 may be coupled to a horizontal support base 198 that may be placed on the portable floor 46. An upper support 200 may be used to couple two or more of the vertical support legs 196 together for stability of the core storage rack 52. In addition, one or more inclined support legs 202 may be coupled to the horizontal support base 198 and the upper support 200 to provide additional stability for the rack 190. In certain embodiments, a counterweight 204 may be placed on the horizontal supports 198 to stabilize the rack 190, e.g., to help prevent the rack 190 from tipping over when the cores of the transformer 10 are placed in the pallet 192. In certain embodiments, one or more holes 206 may be formed in the vertical support legs 196 to enable the pallets 192 to be placed in different vertical positions along the vertical support legs 196. In further embodiments, the rack 190 may accommodate two or more pallets 192 at the same time. In one embodiment, the core storage rack 52 may be obtained from Belcan Corporation of Cincinnati, Ohio.

FIG. 7 is a side view of a group 220 of trailers that may be used to transport the portable transformer repair station 40 from one facility to another. As shown in FIG. 7, the group 220 includes a first trailer 222, a second trailer 224, and a third trailer 226. In further embodiments, fewer or more trailers may be used to transport the portable transformer repair station 40. A cargo area of the trailers 222, 224, and 226 shown in FIG. 7 may be defined by a length 228 and a height 230. In certain embodiments, the length 228 may be between approximately 11 m to 18 m, 13 m to 16 m, or 14 m to 15 m, and the height 230 may be between approximately 2 m to 3 m, 2.4 m, to 2.8 m, or 2.5 m to 2.7 m. The trailers 222, 224, and 226 may include one or more fabric curtains to reduce the weight of the trailers. For example, the curtains may be made from PVC-coated polyester fabrics. In certain embodiments, the first trailer 222 may be configured to transport the portable building 42 and the core storage racks 52, the second trailer 224 may be configured to transport the portable oven 48 and the electric heaters 50, and the third trailer 226 may be configured to transport the portable floor 46 and the HVAC units 54. In other embodiments, the various components of the portable transformer repair station 40 may be arranged differently on the trailers 222, 224, and 226. In one embodiment, the trailers 222, 224, and 226 may be obtained from Utility Trailer Manufacturing Company of City of Industry, Calif.

FIG. 8 is a flowchart of a process 240 that may be used to dry the core and coils of the transformer 10 using the portable transformer repair station 40. In a first step 242, the portable transformer repair station 40 is transported to a local site using the group 220 of trailers 222, 224, and 226. In other embodiments, other transportation vehicles may be used to transport the portable transformer repair station 40 including, but not limited to, trucks, cars, vans, boats, trains, aircraft, and other vehicles. In a second step 244, the portable floor 46 is assembled and laid out at the local site. For example, the floor 46 may be placed on bare ground or on one or more sheets of a material (e.g., plywood), but generally the floor 46 need not be placed on a permanent foundation (e.g., concrete slab). In a third step 246, the portable building 42 is assembled on top of the portable floor 46. In a fourth step 248, the portable oven 48 is assembled and placed inside the portable building 42. In certain embodiments, the portable oven 48 is placed in the transformer repair space 44 inside the portable building 42. In a fifth step 250, the core and coils of the transformer 10 are placed within the portable oven 48 to be dried using the heaters 50, for example. In certain embodiments, the portable oven 48 may include a temperature controller to adjust the heaters 50. For example, the temperature controller may be configured to maintain a threshold temperature inside the portable oven 48 based on feedback from the one or more sensors 174 disposed in the portable oven 48. Maintenance of the temperature at or above the threshold, or level, may enable the core and coils of the transformer 10 to dry within a specified period of time (e.g., two to three weeks). Once dry, the core and coils may be placed within the transformer 10 to be placed back in service. The steps above may be performed in reverse order to disassemble the portable transformer repair station 40 and place it on the group 220 of trailers 222, 224, and 226 to be transported to another transformer facility.

For example, the process 240 may be part of larger process, or procedure, for performing maintenance on large power distribution transformers 10. First, the facility (e.g., power plant) may be surveyed to identify a suitable site (e.g., local site) for the portable transformer repair station 40. The local site may be prepared (e.g., graded) if necessary. In addition, the local site may surround, or be adjacent to, a transformer site where the transformer 10 is located. Next, steps 242, 244, and 246 of the process 240 may be performed to erect the portable transformer repair station 40 at the local site. At this point or earlier, the transformer 10 may be taken out of service. Next, the transformer 10 may be prepared for maintenance. For example, fluids (e.g., oil) may be drained and certain components (e.g., radiators) removed from the transformer 10. Next, the core (e.g., winding legs 12, 14, and 16, and upper and lower yokes 18 and 20) and coils (e.g., phase windings 22) may be removed, or un-tanked, from the transformer 10. The preparation and disassembly of the transformer 10 may be performed elsewhere at the facility or in the portable building 42, if it is large enough. If not already in the portable building 42, the core and coils may be moved into the portable building 42 to be further dissembled. The coils may then be shipped to a transformer repair shop, which may be at the facility or remote from it, to be inspected and rewound. As the coils may be smaller and lighter than the transformer 10, shipment of the coils may be less expensive, faster, and less complicated than shipment of the entire transformer 10 to the repair shop, or remote site.

After being rewound, the coils are returned to the facility. Alternatively, replacement coils may be shipped to the facility from the repair shop. The core and coils are reassembled in the portable building 42 and step 250 of the process 240 may be performed to erect the portable oven 48, if not already completed earlier. The core and coils are dried in the portable oven 48, removed, adjusted (if needed), and taken out of the portable building 42 to be inserted, or re-tanked, into the transformer 10. The re-tanking and subsequent steps may be performed in the portable building 42, if it is large enough. After re-tanking, the cover of the transformer 10 is reattached and the transformer 10 filled with oil. Vacuum processing may then be used to remove any remaining air and/or moisture from the transformer 10. After testing, the transformer 10 may be returned to service, and the portable transformer repair station 40 disassembled and placed on the group 220 of trailers 222, 224, and 226 to be removed from the facility and used again elsewhere. Thus, use of the portable transformer repair station 40 may reduce the cost and time associated with the rewind of the transformer 10 and may avoid having to build permanent structures at the facility for tasks associated with transformer maintenance and/or repair.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

1. A system, comprising: a portable transformer repair station, comprising: a portable building comprising a framework, a roof, and walls having a disassembled building configuration and an assembled building configuration, wherein the portable building is configured to be transported in the disassembled building configuration, the portable building is configured to enclose a transformer repair space in the assembled building configuration, and the roof and the walls comprise at least one fabric sheet; a portable floor having a disassembled floor configuration and an assembled floor configuration, wherein the portable floor is configured to be transported in the disassembled floor configuration, the portable floor is configured to be disposed within the portable building in the assembled floor configuration; and a portable oven configured to be disposed within the portable building, wherein the portable oven is configured to remove moisture from a core and coils of a high voltage power transformer.
 2. The system of claim 1, wherein the at least one fabric sheet comprises a flame retardant material and a moisture resistant material.
 3. The system of claim 1, wherein the portable floor comprises a flame retardant material and a moisture resistant material.
 4. The system of claim 1, wherein the portable floor comprises a plurality of floor segments configured to selectively couple together.
 5. The system of claim 4, wherein each segment comprises a cushioning material and a plurality of structural supports.
 6. The system of claim 1, wherein the portable oven comprises a portable heater coupled to a portable transformer enclosure, and the portable transformer enclosure comprises insulated metal walls.
 7. The system of claim 1, wherein the portable oven comprises a heat source, at least one sensor, and a controller, wherein the controller is responsive to feedback from the at least one sensor to maintain a temperature level for the core and coils of the high voltage power transformer.
 8. The system of claim 1, comprising a portable heating and air conditioning unit configured to heat or air condition the transformer repair space.
 9. The system of claim 1, comprising a transformer rack configured to support core laminations of the high voltage power transformer.
 10. The system of claim 1, comprising at least one trailer or vehicle having a cargo area configured to transport the portable transformer repair station.
 11. A system, comprising: a portable transformer repair station, comprising: a portable transformer enclosure comprising walls surrounding an interior chamber configured to house a core and coils of a high voltage power transformer; a moisture removal unit configured to remove moisture from the interior chamber; and a temperature controller configured to adjust the moisture removal unit to reduce a moisture level below a threshold moisture level in the interior chamber to substantially dry the core and coils of the high voltage power transformer.
 12. The system of claim 11, wherein the moisture removal unit comprises a heater, a heat exchanger, an induced draft fan, a coalescing filter, or a combination thereof.
 13. The system of claim 11, wherein the portable transformer enclosure comprises an oven, and the moisture removal unit comprises a heater.
 14. The system of claim 13, wherein the oven comprises a portable metal enclosure with a framework, a roof, and walls having a disassembled oven configuration and an assembled oven configuration, wherein the portable metal enclosure is configured to be transported in the disassembled oven configuration, and the portable metal enclosure is configured to house at least one coil of the high voltage power transformer in the assembled oven configuration.
 15. The system of claim 11, wherein the portable transformer repair station comprises a portable building with a framework, a roof, and walls having a disassembled building configuration and an assembled building configuration, wherein the portable building is configured to be transported in the disassembled building configuration, and the portable building is configured to house the portable transformer enclosure in a transformer repair space in the assembled building configuration.
 16. The system of claim 11, wherein the portable transformer repair station comprises a portable floor having a disassembled floor configuration and an assembled floor configuration, wherein the portable floor is configured to be transported in the disassembled floor configuration, and the portable floor is configured to support the portable transformer enclosure in the assembled floor configuration.
 17. A method, comprising: transporting a portable transformer repair station to a local site surrounding a transformer site, wherein the portable transformer repair station comprises a portable building, a portable floor, and a portable oven; assembling the portable floor at the local site; assembling the portable building at the local site; placing the portable oven inside the portable building; and drying a core and coils of a high voltage power transformer in the portable oven.
 18. The method of claim 17, wherein the portable floor comprises a plurality of floor segments, and the portable building comprises at least one fabric layer defining a wall or a roof.
 19. The method of claim 17, comprising rewinding the coils and subsequently drying the core and coils in the portable oven.
 20. The method of claim 19, comprising disassembling the coils from the core of the high voltage power transformer at the local site or the transformer site, receiving the coils without the core at a remote site away from the local site and the transformer site, rewinding the coils at the remote site, receiving the coils at the local site after the rewinding, reassembling the coils with the core of the high voltage power transformer at the local site, and drying the core and coils in the portable oven at the local site. 